Here's my experience with the arid reactor. I started off with a golf ball size amount of chaeto. It grew a little bit to maybe a soft ball size in month. Since then, it hasn't really grown anymore. I tried several different photo periods from 8, 12 and 18 hours a day. Still, no more growth. I get some hair algae growing in the reactor also and it grows on the chaeto also.
Maintenance is not bad since I have it in a open location. I did move the dastaco and arid around a bit to make getting to the arid more convenient. I don't clean it often as I don't see much in the way of growth but when I do, I simply remove the led bar, remove the top and into a 5 gallon bucket. I rinse everything off when a hose and a final rinse with RODI. Rinse the chaeto and replace.
My tank has very low nutrients so I'm not sure if it's due to the arid or other means. I tested no3 and po4 today and results were no3=1 and po4=.02, tested with salifert and hanna ulr. I'm going to dose the provided nitrate solution to try and bring up nitrates a bit. I'm not really sure I even need the arid reactor on this system to be honest.
It's crazy because I have close to 50 or just a little over 50 fish, about 8 tangs, some fairly large. I feed the fish 2-3 times a day with 6-8 cubes of frozen each feeding. If I feed from a flat pack, I break off big chunks of food, I think this tank gets fed a lot but it still has low nutrients.